Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India

doi:10.4236/jep.2011.26082

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Journal of Environmental Protection, 2011, 2, 710-719

doi:10.4236/jep.2011.26082 Published Online August 2011 (http://www.SciRP.org/journal/jep)

Ecotoxicity and Ecosystem Health of a Ramsar

Wetland System of India

U. P. Nasir1*, P. S. Harikumar2

1Senior Scientific Assistant, Central Pollution Control Board, Zonal Office-Vadodara, Gujarat, India; 2Scientist & In-Charge, Central

Water Analysis Laboratory, Centre for Water Resources Development and Management, Kozhikode, Kerala, India.

Email: nasirchemistry@yahoo.com, [email protected]

Received March 22nd, 2011; revised May 4th, 2011; accepted June 14th, 2011.

ABSTRACT

In this study one econ omically important Ramsar wetland system of India, Vembanad wetlan d system, is studied to de-

termine the environmental pollutio n. Six surfa ce sediment samples collected from two extreme zones of the wetland sys-

tem were analyzed for heavy metals such as Copper, Zinc, Manganese, Cadmium, Lead, Nickel and Mercury. Highest

metal concentration was found at industrial zone and lowest concentration was detected at southern upstream of the

wetland system. The results showed that the pollution level is significant in the industrial zone. Comparison of the re-

sults with different sediment quality g uidelines indicated ultra high degree of contamination in th e industrial zone. The

numerical value of degree of contamination, pollution load index, sum of toxic units, enrichment factor and geo-accu-

mulation index confirmed the above fact. Based on National Oceanic and Atmospheric Administration Guidelines, the

health of the ecosystem was seriously impaired with frequent occurring of biological effects in the industrial zone. The

percentage of heavy metal calculated with respect to the industrial zone as the base line and the correlation analysis

with organic matter indicated that, mobility of the specific metal has higher impact on its concentration at the fresh

water region of the wetland.

Keywords: Heavy Metal, Sediment Quality Guidelines, Degree of Contamination, Pollution Load Index, Index of

Geo-Accumulation

1. Introduction

Sediments are the layers of relatively finely divided mat-

ter covering the bottom of rivers, streams, lakes, reser-

voirs, bays, estuaries and ocean. Unlike water quality

which is susceptible to seasonal variation, dependent on

in and out flow and weather, sediment quality is more

constant and will have more farfetched implications. As-

sessment of sediments in a complex aquatic system re-

sulted in a better understanding of the adverse impacts

that contaminants in sediments pose to fish, wild life and

humans who depend this impacted waterways. Therefore

apart from polluted water, fate of contaminated sediment

has been chosen as one of the aspects responsible for

ecological decline. Lake sediments provide a useful ar-

chive of information on changing lacustrine and water-

shed ecology [1]. The composition of the sediment se-

quences provides the best natural achieves of recent en-

vironmental changes [2].

Sediment is a habitat and major nutrient source for

aquatic organisms. Sediment analysis is important in eva-

luating qualities of total ecosystems of a water body in

addition to water sample analysis practiced for many

years because it reflects the long term quality situations

independent of the current inputs [3] and it is the ultimate

sink of contaminants in the aquatic system [4]. Accumu-

lation of heavy metals occur in upper sediment of the

aquatic environment by biological and geochemical

mechanisms and becomes toxic to sediment dwelling

organisms and fish, resulting in death, reduced growth, or

in impaired reproduction and lower species diversity [5].

Trace elements also occur naturally in rock forming

minerals; hence they can reach the environment from

natural processes [6]. The occurrence of metals in aquatic

ecosystems in excess of natural background loads has

become a problem of increasing concern. Heavy metals

in environment may accumulate to toxic levels without

visible signs. This may occur naturally from normal

geological phenomenon such as ore formation, weather-

ing of rocks and leaching or due to increased population,

urbanization, industrial activities, agricultural practices,

exploration and exploitation of natural resources [7].

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India711

One of the major problems that heavy metals cause

with respect to their effects on aquatic organisms is their

long biological half-life. Therefore, they are among the

most frequently monitored micropollutants, and reliable

techniques have been established for their extraction and

quantification [8-10], since sediment contamination by

heavy metals in rivers and estuaries has become an issue

of increasing environmental concern. Such contamina-

tion is often caused by human activities, including min-

ing, smelting, electroplating and other industrial proc-

esses that have metal residues in their wastes, and by

non-point source surface runoff.

It is accepted that without defensible sediment quality

guidelines it would be difficult to assess the extend of

sediment contamination [11]. Sediments were classified

as non-polluted, moderately polluted and heavily pol-

luted, based on Sediment Quality Guidelines of United

State Environmental Protection Agency [12]. Hakanson

et al. [13] had suggested a contamination factor (Cif) and

the degree of contamination (Cd) to describe the con-

tamination of given toxic substance. Tomlinson et al. [14]

had employed a simple method based on pollution load

index (PLI) to assess the extent of pollution by metals in

estuarine sediments. The need for chemical guidelines

that could be used to predict adverse biological effects in

contaminated sediments lead to the development of

sediment quality guidelines [15-18]. The ecotoxicologi-

cal sense of heavy metal contamination in sediments was

determined using sediment quality guidelines developed

for marine and estuarine ecosystem [19]. The potential

acute toxicity of contaminants in sediment sample can be

estimated as the sum of the toxic units (∑TU) defined as

the ratio of the determined concentration to PEL value

[20]. Pollution will be measured as enrichment factor

(EF), which is the amount or ratio of the sample metal

enrichment above the concentration present in the refer-

ence station or material [21,22]. Sediment geo accumula-

tion index (GeoI) is the quantitative check of metal pol-

lution in aquatic sediments [23]. These impacts were

assessed by means of the geo-accumulation index (Igeo)

[24] and Igeo classification is reported based on the

chemical analysis of the bulk sediments. The Igeo has

been widely utilized as a measure of pollution in fresh-

water [25-27] and marine sediments [28-30].

The over all objective of this research work was to

evaluate the degree and extend to which the heavy metal

contamination has affected the Vembanad wetland sys-

tem, one of the Ramsar site in the south west coast of

India. In this study heavy metals such as copper, zinc,

manganese, cadmium, lead, nickel and mercury in sur-

face sediments were analysed using different sediment

quality guidelines. The numerical value of different

sediment quality indices such as degree of contamination,

pollution load index, sum of toxic units, enrichment fac-

tor and geo-accumulation index were also calculated for

the data interpretation. Hence the present study aimed to

understand the pollution load at industrial region of the

wetland system and its impact towards the fresh water

region of the Vembanad Lake.

The Vembanad wetland system (Latitude 9˚30' and

10˚12'; Longitude 76˚10' and 76˚29') is a complex aquatic

system of coastal backwaters, lagoons, marshes, man-

groves and reclaimed lands with an intricate network of

natural and man made channels and its associated drain-

age basins are situated in the humid tropical region on

the south west coast of the Indian peninsula. The total

area of the wetland system is 2195 km2. This system in-

cludes the Vembanad backwaters and the lower reaches

of the five rivers draining in to it. The five rivers which

drain in to the Vembanad Lake are Muvattupuzha,

Meenachil, Manimala, Pamba and Achenkoil. All these

rivers originate from the Western Ghats, flow westwards

through the wetland system and join the Lakshadweep/

Arabian Sea. The wetland is typically divided into two

distinct segments, the freshwater dominant southern zone

and the salt-water dominant northern zone both separated

by a bund at Thanneermukkom. The estuarine zone and

organically rich sedimentary substratum of the inshore

region makes it a highly preferred and desirable habitat

for shrimps breeding. Vembanad is renowned for its live

clam resources and sub-fossil deposits. Vembanad wet-

land has been designated as a Ramsar Site in November

2002.

The wetland system is facing many problems, which

include; pollution due to industrial, agricultural and do-

mestic effluents. It is estimated that nearly 260 million

liters of effluents reach the estuaries daily form the in-

dustries located in the northern part of the wetland sys-

tem [31]. The Cochin estuarine system receives effluents

containing a large dose of heavy metals [32]. The distri-

bution and toxicity of heavy metals in core sediments

also indicated severe pollution in the wetlands [33,34].

The increasing loads of sewage and industrial waste have

created conditions that are extremely destructive to flora

and fauna. During the tidal activity pollutants from the

northern side moves towards the southern side making

the fresh water system also threatened. In addition agri-

cultural inputs from the lands located around the lake

also pollute the freshwater region of the lake.

Sampling Stations

Six sampling stations were selected in the wetland sys-

tem starting from the northern industrial region to the

southern fresh water region. Six surface sediment sam-

ples were collected from each site, using a gravity corer

with PVC core-liner. Four centimeters of the surface

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India

712

sediments were extracted from the core-liner and placed

in labeled polythene bags. In the laboratory the sediments

were air-dried [23] to a constant weight and homoge-

nized with a pestle and mortar, in order to normalize for

variation in grain size distribution. The sampling sites are

marked in the area map (Figure 1).

2. Analytical Methods

For the digestion of the sediment sample one gram of

dried and homogenized sediment sample was weighed

into 250 ml beaker. An empty beaker was included in the

analysis as a reagent empty blank. 50 ml of distilled wa-

ter was added to the sample. The digestion was per-

formed with a mixture HNO3 and HClO4. Digestion was

continued until the volume was reduced to about 15 ml.

The beakers were allowed to cool to room temperature.

The digests were then filtered into a 50ml volumetric

flask and made up to the volume with distilled water [35].

The digested samples were analyzed for heavy metal

following Atomic Absorption Spectrophotometer [15] by

Thermo M5 series. The concentration of manganese,

cadmium, copper, lead, nickel, zinc and mercury were

determined in sediment samples and the values are re-

ported in units of mg/Kg.

The contamination factor for the sediment samples

were calculated by the equation;

Figure 1. Area map of Vembanad wetland system showing

the sediment sampling sites.

Contamination Factor (CF) = Metal content in sedi-

ment/Background level of metal (1)

The method proposed by Tomlinson et al. [14] had

employed in the present study to find the sediment pollu-

tion load index (PLI) which is given by the equation;

PLI = (Product of n number of CF values)1/n (2)

Enrichment factors (EF) for metal concentration in

sediments at all the stations was calculated and used for

comparison. The following equation was used to calcu-

late the EFc values.

EFc = X/Fe (sediment)/X/Fe (Earth’s crust) (3)

where X is the metal studied and X/Fe is the ratio of the

concentration of element X to iron. Iron was chosen as

the element of normalization because natural sources

(98%) vastly dominate its input. The crustal abundance

data of Bowen [36] were used for all EF values.

The geoaccumulation index Igeo values were calcu-

lated for different metals as introduced by Muller [37] is

as follows:

Igeo = Log2(Cn/1.5*Bn) (4)

where Cn is the measured concentration of element n in

the sediment simple and Bn is the geochemical back-

ground for the element n which is Esther directly meas-

ured in pre civilization sediments of the area or taken

from the literature (average shale values). The factor 1.5

was introduced to include the possible variation of the

background values that are due to lithological variations.

3. Results

One of the simple ways of assessing the level of pollu-

tion in an aquatic ecosystem is the comparison with dif-

ferent sediment quality guidelines. The range and the

mean concentration of heavy metals determined in the

sediment samples and their comparative assessment with

different international sediment quality guidelines are

tabulated in Tabl e 1. The concentration of copper varied

from 38.7 mg/Kg to 1723.75 mg/Kg. Zinc has a variation

from 70.7 mg/Kg to 1963.67 mg/Kg. Manganese con-

centration in the surface sediments according to the pre-

sent investigation varied from 320.51 mg/Kg to 15586.88

mg/Kg. Cadmium in the sediment ranges from 0.27

mg/Kg to 6.35 mg/Kg. The concentration of lead ranged

from 21.70 mg/Kg to 162.59 mg/Kg. Nickel has a varia-

tion from 49.59 mg/Kg to 75.70 mg/Kg.

The level of contamination in aquatic system can be

assessed by determining a factor called the degree of

contamination (mCd). Elemental background concentra-

tion reported for continental crust was used as the refer-

ence value. The calculated value for the degree of con-

tamination ranges from 1.47 to 35.39. The extend of pol-

lution in an aquatic environment can be evaluated by a

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India

713

Table 1. Concentration range of different heavy metals and its comparison with different SQGs.

Ontario MOE NOAA SQGFDEP SQGCCME USEPA

Element

mg/Kg Mean Range

Low Severe ERL ERMTELPEL IGM PEL

CSCR SQG

SQG

Cu 799.15 38.87 - 1723.75 16 110 34 270 18.711035.719760 - 125 <25 25 - 50>50

Zn 528.21 70.07 - 1963.67 120 820 150410 124.0270 70 - 400 <90 90 - 200>200

Mn 4928.9 320.51 - 15586.88 460 1110 1500 - 3000 - - -

Cd 6.63 0.27 - 26.35 0.6 10 1.29.6 0.684.200.6 3.53 - 8 - - -

Pb 66.40 21.70 - 162.59 31 250 46.7218 30.211035 91.3100 - 400 <40 40 - 60>60

Ni 64.35 49.59 - 75.70 16 75 20.951.615.943 123315100 <20 20 - 50>50

ERL-Effect Range Low, ERM- Effect Range Median, TEL-Threshold Effect Level, PEL-Probable Effect Level, IGM-Interim sediment quality Goals, NP-Non

Polluted, MP-Moderately Polluted, HM-Heavily Polluted.

simple method based on pollution load index (PLI). The

world average concentration of elements reported for

Shale was taken as the reference for PLI. Station 6/VL

reported lower PLI value (1.02) and the highest (12.92)

was reported for station 2/VL. The potential acute toxic-

ity of contaminants in sediment samples can be estimated

as the sum of toxic units (∑TU) defined as the ratio of

determined concentration to PEL values. The TU values

also show the same trend as like mCd and PLI. The dif-

ferent values observed for degree of contamination, pol-

lution load index and sum of toxic units are summarized

in Table 2. All the values indicated metal contamination

in the Vembanad Lake.

A common approach to estimate how much the sedi-

ment is impacted (naturally and anthropogenically) with

heavy metal is to calculate the enrichment factor (EF) for

metal concentrations above uncontaminated background

levels. The average standard reported for Shale was used

as the reference value in the present study. The enrich-

ment factors for different metals in different stations are

tabulated in Tabl e 3 . Index of geochemical accumulation

(Igeo) has been used widely to evaluate the degree of

metal contamination or pollution in terrestrial, aquatic

and marine environment. World average reported for

Shale was used as the control in the present study. Geo-

accumulation index for different stations is summarized

in Table 4.

Correlation matrix provides clues about the carrier

substances and the chemical association of these metals

in the ecosystem. In the present study Pearson’s correla-

tion has employed for different metals with organic mat-

ter. The correlation matrix is given in Table 5.

4. Discussion

4.1. Spatial Variation of Heavy Metals

Figure 2 represents the spatial variation of different

heavy metals in the surface sediments of Vembanad wet-

land system. The mean concentration of different heavy

metals follows the order manganese > copper > zinc >

lead > nickel > cadmium > mercury. The average con-

centration of copper is 799.15 mg/Kg, which was above

the all compared sediment quality guidelines. The high-

est deposition was found in the Cochin bar mouth and

lowest was reported in the station 6/VL, which is in the

southern end. High level of copper indicates a higher

input of organic matter deposition, which might be from

urban and industrial waste water sediment deposition.

The average concentration of zinc is 528.21 mg/Kg,

which was also above the all sediment quality guidelines.

Manganese in earth crust is 1060 mg/Kg; in soils it is 61 -

1060 mg/Kg. The station 2/VL has reported 15586.88

which is far away from the guideline values. A uniform

decreasing trend was observed for manganese except for

the station 1/VL. The average abundance of cadmium in

the earth crust is 0.16 ppm; in soils it is 0.1 - 0.5 mg/Kg.

Increased cadmium concentration might be related to

industrial activity, atmospheric emission and deposition

of organic and fine grain sediments. Lead is considered

as a good indicator of pollution by urban run-off water.

The use of gasoline is mainly responsible for the lead

pollution especially in urban area. The average concen-

tration of lead in the present study is 66.40 mg/Kg, which

is in the category of highly polluted sediments according

to United State Environmental Protection Agency Guide-

lines. The background value of nickel in the earth crust is

1.2 mg/Kg; in soil it is 2.5 mg/Kg. Nickel is used princi-

pally in its metallic form combined with other metals and

nonmetals as alloys. The mean value of nickel is 64.35

mg/Kg, which is above the United State Environmental

Protection Agency Guidelines for highly polluted sedi-

ments. The mercury pollution is severe in the sediments

of the Cochin bar mouth with a concentration of 4.91

mg/Kg.

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India

714

Table 2. Spatial variation of heavy metals and different index values.

Element/Stations 1/VL 2/VL 3/VL 4/VL 5/VL 6/VL Continental Crust Average shale

Cu mg/Kg 1346.25 1588.13 1723.75 47.60 50.30 38.87 55.00 45.00

Zn mg/Kg 578.11 1963.67 70.07 223.00 156.68 177.75 70.00 95.00

Mn mg/Kg 4040.00 15586.88 8714.38 501.67 320.51 410.00 950.00 900.00

Cd mg/Kg 7.03 26.35 5.23 0.27 0.35 0.55 0.20 0.30

Pb mg/Kg 27.18 78.27 162.59 28.65 80.03 21.70 12.50 20.00

Ni mg/Kg 70.56 72.82 49.59 64.73 75.70 52.67 75.00 68.00

Hg, mg/Kg 0.56 0.23 4.91 0.136 0.345 0.270

mCd 12.54 35.39 13.55 1.51 2.11 1.47

PLI 5.48 12.92 5.52 1.09 1.23 1.02

SUM TU 17.94 30.39 19.81 3.09 3.61 2.56

mCd: Degree of Contamination, PLI- Pollution Load Index, SUM TU- Sum of Toxic Units.

Table 3. Enrichment factor calculated for the sediment samples of Vembanad wetland system.

Enrichment Factor

Element/Stations

1/VL 2/VL 3/VL 4/VL 5/VL 6/VL

Cu 19.94 23.53 25.54 0.71 0.75 0.58

Zn 4.06 13.78 0.49 1.56 1.10 1.25

Mn 2.99 11.55 6.46 0.37 0.24 0.30

Cd 15.61 58.56 11.61 0.59 0.79 1.21

Pb 0.91 2.61 5.42 0.95 2.67 0.72

Ni 0.63 0.71 0.49 0.63 0.74 0.52

Table 4. Sediment geo-accumulation index (Igeo) calculated for sediments of Vembanad wetland system.

Index of Geo-accumulation

Element/Stations

1/VL 2/VL 3/VL 4/VL 5/VL 6/VL

Cu 4.32 4.56 4.67 −0.50 −0.42 −0.80

Zn 2.02 3.78 −1.02 0.65 0.14 0.32

Mn 1.58 3.53 2.69 −1.43 −2.07 −1.72

Cd, 3.96 5.87 3.54 −0.75 −0.35 0.28

Pb, −0.14 1.38 2.44 −0.07 1.42 −0.47

Ni −0.67 −0.49 −1.04 −0.66 −0.43 −0.95

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India715

Table 5. Pearson Correlation Matrix for different heavy metals with organic matter.

Cu Zn Mn Cd Pb Ni Hg O.M

Cu 1.00 0.50 0.84 0.68 0.57 −0.08 0.57 −0.27

Zn 1.00 0.81 0.97 −0.04 0.48 −0.32 0.53

Mn 1 0.93 0.50 0.08 0.29 0.11

Cd 1.00 0.19 0.34 −0.07 0.37

Pb 1.00 −0.31 0.87 −0.31

Ni 1.00 −0.65 0.86

Hg 1.00 −0.70

O.M 1.00

O.M: Organic Matter.

Figure 2. Spatial variation of different heavy metals in the surface sediments.

4.2. Sediment Quality Indices

The index value of various sediment quality indices such

as degree of contamination, pollution load index and sum

of toxic units are depicted in Figure 3. The degree of

contamination (mCd) in an ecosystem is usually ex-

pressed by the following terminologies.

mCd ≤ 1.5 nil to very low degree of contamination

1.5 ≤ mCd < 2 low degree of contamination

2 ≤ mCd <4 moderate degree of contamination

4 ≤ mCd <8 high degree of contamination

8 ≤ mCd < 16 very high degree of contamination

16 ≤ mCd <32 extremely high degree of contamination

mCd ≥ 32 ultra high degree of contamination

Comparison of the results with the above terminol-

ogies indicated that ultra degree of contamination is ob-

served at the station 2/VL which is located near the out-

lets of many industries. The other two stations 1/VL and

2/VL, near by the industrial units indicated very high

degree of contamination. Moving towards the south a

comparative decrease in the contamination was observed.

The two stations, 4/VL and 5/VL experienced low degree

of contamination. Sediment in the southern end indicated

very low degree of contamination. The spatial variation

of degree of contamination indicated that the movement

of contaminated water and sediments from estuarine re-

gion to southern half of Vembanad wetland system at the

time of high tide contaminated the fresh water region to

some extend.

The pollution load index of the wetland follows the

same order as the degree of contamination. If the PLI

value is greater than one it indicates pollution and if it is

less than one it shows no pollution. The PLI can provide

information about the quality of the environment, which

provides valuable information to the decision makers on

the pollution level of the area. Hence according to PLI

values all the stations in the wetland system is polluted.

The sediment quality guidelines of the National Ocea-

nographic and Atmospheric Administration (NOAA) of

the Unite States shows Effect Range Low (ERL) and

Effect Range Median (ERM) values, which represents

the percentile ranges of toxicity tolerance in bioassay

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India

716

Figure 3. Variation of different sediment quality index val-

ues for Vembanad wetland system.

tests for aquatic and benthic biota. These effects are

given by

Metal < ERL minimal effect range biological effects

are rarely observed

ERL < Metal < ERM moderate effect range biological

effects occur occasionally

Metal > ERM probable effect range biological effects

occur frequently

The mean concentration of copper and zinc exceeded

the ERM limits, which represents a probable effect range

with in which adverse biological effects frequently occur.

Spatial variation of trace elements indicated that biologi-

cal effects are rare in southern half and frequent in estua-

rine side. The potential acute toxicity for the sediments

were determined by calculating the sum of toxic units

and showed similar trend like mCd and PLI.

The enrichment factor method normalizes the meas-

ured heavy metal content with respect to a sample refer-

ence such as iron. It can be used to differentiate between

the metal originating from anthropogenic activities and

those from natural procedure, and to assess the degree of

anthropogenic influence. Five contamination categories

are recognized on the basis of the enrichment factor,

which are

EF < 2 deficiency to minimal enrichment

EF 2 - 5 moderate enrichment

EF 5 - 20 significant enrichment

EF 20 - 40 very high enrichment

EF > 40 extremely high enrichment

A value of 0.5 ≤ EF ≤ 1.5 suggests that traces of metal

may be due to crystal materials or natural weathering

processes. Samples having EF value greater than 5 are

considered to be contaminated with that particular ele-

ment. Figure 4 represents all the EF values of the heavy

metals. The station 2/VL showed very high enrichment

for the metal cadmium. It is presumed that high EF val-

ues indicate an anthropogenic source of heavy metals,

mainly from activities such as industrialization and ur-

banization. Comparatively less enrichment was observed

in samples of southern region. But according to Khan et

al. [38] EF value less than one are considered significant.

Areas with EF values <1 should be viewed with caution

as they imply preferential release of these metals, making

them bioavailabe.

The Index of geo-accumulation calculated for the de-

gree of metal pollution is assessed in terms of seven con-

tamination classes based on the increasing numerical

value of the index as follows:

Igeo

Igeo < 0 unpolluted

0 <= Igeo < 1 unpolluted to moderately polluted

1 <= Igeo < 2 moderately polluted

2 <= Igeo < 3 moderately polluted to strongly polluted

3 <= Igeo < 4 strongly polluted

4 <= Igeo < 5 strongly polluted to very strongly pol-

luted

Igeo >= 5 very strongly polluted

Figure 5 represents the geo-accumulation index for

different heavy metals in the wetland. It indicates strong

pollution in the industrial zone and unpolluted to moder-

ate pollution in the freshwater region. Elements copper

Figure 4. Variation of enrichment factor along different

stations.

Figure 5. Variation of geo-accumulation index for different

stations.

Ecotoxicity and Ecosystem Health of a Ramsar Wetland System of India717

and cadmium have higher values in northern half where

as it is very low in southern side.

4.3. Pearson’s Correlation Matrix

Correlation analysis of heavy metals with organic matter

present in the sediment was carried out. Zinc and nickel

have good correlation with organic matter where as

mercury have a strong negative correlation. The element

cadmium has good correlation with all other elements

except mercury. Copper also has good correlation with

other metals except nickel and organic matter. The per-

centage of different metals in the sediments of fresh wa-

ter region with reference to industrial zone was calcu-

lated. The concentration of nickel in both the regions was

same, which indicated the higher mobility of the metal

nickel. The lowest percentage was reported for copper,

which indicated its lower mobility. The above facts were

conformed from the correlation matrix, where nickel has

good correlation with organic matter and copper have no

correlation. Hence the concentration of the heavy metals

in fresh water is a proportionate of the mobility of metal

and contamination load at industrial side.

5. Conclusions

The study of “Ecotoxicity and ecosystem health of a

Ramsar wetland system of India” showed a clear pattern

of anthropogenic impact on Vembanad wetland system.

From the observation it is clear that manganese and cop-

per showed more pronounced level followed by zinc,

lead, nickel, cadmium and mercury. Comparison of

heavy metal concentration with different international

sediment quality guidelines indicated that most of the

heavy metal concentration in the northern side of the

wetland system has crossed the extreme limits where as

southern half is with in the range of guideline values. The

assessment of level of contamination by calculating the

degree of contamination for different stations confirmed

ultra degree of contamination at station near by industrial

area. Enrichment factor determined for the deferent

heavy metals indicated anthropogenic origin of heavy

metal in estuarine side. Index of geo-accumulation was

also showed the same trend like enrichment factor. Ac-

cording to NOAA guidelines the health of the ecosystem

was seriously impaired with frequent biological effects

were occurring in estuarine side. The extend of pollution

at the fresh water region also depends on the mobility of

the specific metal. Nickel has higher mobility which has

hundred percentage contribution, where as copper is less

mobile which indicated its lowest contribution from the

industrial zone. Anthropogenic source from the industrial

activities at the upstream of the wetland contributed huge

load of heavy metals to the estuarine region which is

seriously attacking the fresh water region of the Vemba-

nad wetland system.

6. Acknowledgements

The authors wish to express their gratitude to the De-

partment of Science and Technology (DST), Government

of India for the financial assistance to carryout the re-

search work.

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